Developments in polymerization technology have provided more efficient, highly productive and economically enhanced catalyst systems and processes. Especially illustrative of these advances is the development of bulky ligand metallocene-type catalysts and of Group 15 metal containing catalysts. To utilize these systems in industrial slurry or gas phases processes, it is useful that they be immobilized on a carrier or support such as, for example silica or alumina. Bulky ligand metallocene-type catalysts, however, typically exhibit lower activity when supported than in the corresponding homogeneous or non-supported catalyst systems. This “support effect” is especially dramatic when the catalyst system utilizes a stoichiometric activator, for example a bulky ligand metallocene-type/non-coordinating anion catalyst system.
In a typical method to prepare a supported catalyst system, the catalyst and activator are combined in a suitable solvent then added to the support or carrier material. However, systems utilizing stoichiometric activators are often difficult to dissolve in hydrocarbon solvents and as a result are difficult to combine with a support material. Thus, there is a need to improve the solubility of catalyst compounds, especially those utilizing stoichiometric activators, to facilitate the preparation of supported catalysts, and also to reduce the “support effect” when using such catalyst systems.
U.S. Pat. No. 5,747,404 discloses a polysiloxane supported metallocene catalyst where the metallocene-type organometallic catalyst is directly bonded to a silicon atom in a siloxane polymeric oil.
PCT WO 99/14269 discloses organopolysiloxane microgel particles, having a diameter of 5 to 200 nm, with organo-aluminum compounds immobilized thereon, which may be used as cocatalyst with metal compounds of the IV, V, VI and VIII sub-groups of the periodic table, for oligomerization cyclization or polymerization of olefins.
While these catalyst systems and methods have been described in the art, a need exists for an improved catalyst system and method for preparing it.